U2021XA Datasheet, PDF (5/20 Pages) Keysight Technologies – U2020 X-Series USB Peak and Average Power Sensors

05 | Keysight | U2020 X-Series USB Peak and Average Power Sensors – Data Sheet
Additional U2020 X-Series
features
List mode
List mode is a mode of operation where
a predefined sequence of measurement
steps can be programmed into the power
sensor and repeatedly executed as many
times as required. This mode is suitable
for power and frequency sweeps which
normally require changing the parameters
via the appropriate SCPI commands before
performing a measurement. The hardware
handshaking communication between
the power sensor and the signal source
provides the fastest possible execution
time in performing the test sequences.
List mode enables users to setup the
number of measurements, the number
and duration of timeslots, the start and
stop frequency for sweeping and the
exclusion interval. This is especially useful
for speeding up measurements for eight
time-slotted GSM/EDGE bursts, LTE-TDD
or WLAN frames and sub-frames.
For more information, please refer to
the programming examples in the
U2020 X-Series Programming Guide.
Variable aperture size
In average only mode and at normal
measurement speed, the time interval
length used to measure the average power
of the signal can be adjusted by setting
the aperture size to between 125 µs and
200 ms. This is useful for CW signals
and noise-like modulated signals such
as LTE-FDD and WCDMA by performing
measurements over the full frames or
sub-frames.
Decreasing the aperture size will improve
the measurement throughput but reduce
the signal-to-noise ratio of the measured
signal. However, increasing the aperture
size will improve the signal-to-noise ratio
of the measured signal but reduce the
measurement throughput.
Table 1. Aperture size
Measurement Default
speed
aperture size
NORMal
50 ms
DOUBle
26 ms
FAST
2 ms
Adjustable
Yes
No
No
Average only mode external
trigger
The U2020 X-Series also supports external
trigger in average only mode. The external
trigger can be used to synchronize the
measurement capture with signal burst
timing. By adjusting the aperture size and
trigger delay, users have greater control
on which portion of the waveform is being
measured. This function complements the
time-gated function in normal mode (peak
mode) by offering a wider power range
and faster measurement speed, although
it comes without trace display.
Auto burst detection
Auto burst detection helps the measure-
ment setup of the trace or gate positions
and sizes, and triggering parameters on a
large variety of complex modulated signals
by synchronizing to the RF bursts. After
a successful auto- scaling, the triggering
parameters such as the trigger level,
delay, and hold- off are automatically
adjusted for optimum operation. The trace
settings are also adjusted to align the RF
burst to the center of the trace display.
20-pulse measurements
The U2020 X-Series can measure up to
20 pulses. The measurement of radar
pulse timing characteristics is greatly
simplified and accelerated by performing
analysis simultaneously on up to 20
pulses within a single capture. Individual
pulse duration, period, duty cycle and
separation, positive or negative transition
duration, and time (relative to the delayed
trigger point) are measured. The U2020
X-Series also supports automatic pulse
tilt (or droop) measurements via SCPI
command.
High average count reset
When high averaging factors have
been set, any rapid adjustments to the
amplitude of the measured signal will
be delayed due to the need to allow
the averaging filter to fill before a new
measurement can be taken at a stable
power level. The U2020 X-Series allows
you to reset the long filter after the final
adjustment to the signal’s amplitude has
been made.
Gamma correction
In an ideal measurement scenario, the
reference impedance of the power sensor
and DUT impedance should equal the
reference impedance (Zo); however, this is
rarely the case in practice. The mismatch
in impedance values results in a portion of
the signal voltage being reflected, and this
reflection is quantified by the reflection
coefficient or gamma.
Using gamma correction function, users
can simply input the DUT’s gamma into
the sensor via SCPI commands for
mismatch correction. This yields more
accurate measurements.
S-parameter correction
Additional errors are often caused by
components that are inserted between
the DUT and power sensor, such as in
base station testing where a high power
attenuator is connected between the
sensor and base station to reduce the
output power to the measurable power
range of the sensor.
The S-parameters of these components
can be obtained with a vector network
analyzer in the touchstone format, and
inputted into the sensor using SCPI
commands. This error can be corrected
with the S-parameter correction so that
the sensor will measure as though it is
connected directly to the DUT, giving users
highly accurate power measurements.